Abstract CT039: Intratumoral CD40 agonist sotigalimab with pembrolizumab induces broad innate and adaptive immune activation in local and distant tumors in metastatic melanoma

Abstract The use of immune-checkpoint inhibitors (CPI) has become an important modality in the treatment of metastatic melanoma (MM). However, most patients (pts) do not experience durable responses and new treatment options are needed to improve clinical outcomes. Our pre-clinical studies have demonstrated that intratumoral CD40 activation synergizes with anti-PD-1 based therapy and induces systemic and distant anti-tumor effects. In this ongoing phase I/II study, we assessed intratumoral sotigalimab (APX005M), a CD40 agonist antibody, in combination with systemic pembrolizumab in CPI treatment naïve, unresectable stage III or IV MM. A total of 40 participants will be enrolled. As of December 15, 2021, 30 pts were enrolled. Pts received sotigalimab every 3 weeks for a total of 4 doses. The dose escalation portion of the trial has been completed, with 14 pts enrolled in 5 dosing cohorts of sotigalimab at 0.1, 0.5, 1, 3 and 10 mg. The primary objectives include safety and tolerability, determination of the recommended phase 2 dose (RP2D), and assessment of the overall response rate (ORR) by RECIST v1.1. Biomarker analyses of blood and tumor samples were performed to measure immune activation using immunophenotyping including imaging mass cytometry, TCR sequencing, and a cross-cohort comparison of gene expression data (sotigalimab plus pembrolizumab versus anti-PD1 monotherapy). The combination therapy has been well-tolerated, and there were no study discontinuations or death due to treatment-related adverse events (TRAEs). Most common TRAEs were injection-site reactions; six pts experienced grade-3 immune-related adverse events. Efficacy analysis of 30 pts with post-baseline disease evaluations demonstrated an ORR of 50% (5 CR and 10 PR) in distant lesions and a disease control rate of 67%. The ORR at the RP2D of 10 mg is 55% (12/22). Responses were observed in PD-L1 negative pts and those with elevated LDH. Comprehensive transcriptome and immune cell profiling of peripheral blood mononuclear cells and tumor biopsies obtained from local lesions at baseline and 24 hours post sotigalimab injection demonstrate that sotigalimab effectively engaged CD40 pathway. In comparison to anti-PD1 monotherapy, the combination therapy significantly increased expression of genes associated with antigen presentation and effector T cells in local lesions accompanied by an increase in T cell activation genes at distant lesions. Additionally, T cell repertoire analysis demonstrated a significant increase in T cell clonality with expansion of new clones shared between local and distant tumors. Importantly, these immunologic changes were correlated with clinical response. Collectively, this combination therapy is well tolerated and has a notable clinical response rate, accompanied by broad innate and adaptive immune activation at both local and distant lesions. Citation Format: Salah-Eddine Bentebibel, Daniel Johnson, Rodabe Amariae, Daniel McGrail, Srisuda Lecagoonporn, Cara Haymaker, Dzifa Duose, Khalida Wani, Houssein Safa, Isabella Claudia Glitza, Sapna Pradyuman Patel, Michael K. Wong, Hussein Tawbi, Jared Burks, Xiaodong Yang, Patrick Hwu, Cassian Yee, Michael A. Davies, Ravi Murthy, Chantale Bernatchez, Suhendan Ekmekcioglu, Adi Diab, Gregory Lizée. Intratumoral CD40 agonist sotigalimab with pembrolizumab induces broad innate and adaptive immune activation in local and distant tumors in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT039.